Building cooperative security through interdependence was a major imperative underlying the development of the European Union. Yet months after Theresa May triggered Article 50, the Conservative negotiators exhibit a shocking lack of analysis of the challenges and risks posed by Brexit for British - and European - defence and security.
When concerns have been raised, they are airily dismissed by the pro-Leave lobby, which points to NATO and the United States as if they will fill the gap.
Close cooperation among European Green parties and MEPs means that we have more say and greater confidence in the EU's approach to security and defence than NATO's, a primarily military-nuclear alliance that relies on massive levels of military expenditure and US weapons, including nuclear "sharing".
The head of the European External Action Service (EEAS) and High Representative for Foreign Affairs and Security Policy, Federica Mogherini, recently underlined that "peace is a collective cooperative responsibility", which requires wisdom, diplomacy, cooperative political leadership and courage more than weaponry.
Working together with the US, Europe's two nuclear-armed states - Britain and France - pressured NATO and EU members to boycott and vote against the UN's multilateral disarmament talks. Although most NATO states boycotted, it was helpful that the European Parliament overwhelmingly adopted a Green-led resolution in 2016 to support the humanitarian treaty process. Two non-NATO EU members, Austria and Ireland, played key roles in bringing the UN negotiations to fruition, resulting in the adoption of the ground-breaking Treaty on the Prohibition of Nuclear Weapons on 7 July 2017 by 122 UN members out of the 124 present, with one against and one abstention.
Rooted in early agreements on coal and steel production, agriculture, Euratom's nuclear regulation and transboundary legal cooperation, the EU was founded with the deliberate intention of creating interdependencies that would prevent future destructive wars. Some fear that Brexit may embolden France to push its own nuclear and defence agenda for the EU to become more militarised under a French nuclear umbrella.
If Britain withdraws from the Euratom Treaty, this would have a negative impact on the oversight of UK nuclear facilities but could have a positive silver lining if it undermines Anglo-French nuclear weapons research and collaboration instituted in the iniquitous 2010 Teutatus Treaty brokered by David Cameron and Nicolas Sarkozy. And Brexit could well strengthen Scotland's ability to reject Trident and advocate for the UN's Nuclear Prohibition Treaty.
Greens generally support the priority that the EEAS gives to strengthening shared capabilities to prevent and manage security threats, including terrorism and weapons proliferation, and provide humanitarian action where needed. The EU also introduced diplomatic and trade restrictions and incentives to promote human rights, democratic principles, and the rule of law around the world. These shared values are enshrined in Theresa May's bugbear, the European Court of Justice (ECJ), which underpins so many aspects of EU legislation and cooperation.
It has been important for Britain to be part of all these arrangements and decisions. Now, the Tory push against freedom of movement is creating fears about stringent border security being imposed, endangering the 1998 Belfast Agreement that brought peace to Northern Ireland. At the very least, Brexit is set to weaken our influence, rights, responsibilities and access to laws and agreements that provide shared intelligence, environmental protection, expertise and oversight essential for building peace and security.
If Brexit continues to be pursued despite the accumulating evidence that it will be detrimental to UK security and much else, then we need to push hard for similar or, ideally, stronger security safeguards to be established in the UK's legislation and future agreements with other countries. These would have to uphold human rights and international law, and cover a range of issues, from Northern Ireland to principles for effective cooperation on all matters pertaining to human and regional security, environmental protection, nuclear safety, prevention of extremist violence, and tackling the criminal networks that traffic in weapons, drugs and people.
That won't be easy. To avoid the nightmare of wars in the future, we need to do all we can to ensure that Britain and the rest of Europe continue to be close partners, and to prevent Brexit providing a route for nationalist extremists to undermine the EU's essential cooperative security role.